Shuttle assembly for an integrated buffing and grinding system

ABSTRACT

The present invention provides a shuttle assembly for supporting at least one pallet and adapted to cooperate with a moveable working table. The shuttle assembly includes a frame and a structure on the frame for providing at least one loading and unloading platform having an open end adapted to allow transfer of at least one pallet between the loading and unloading platform and the moveable working table. The shuttle assembly also includes a clamp assembly located opposite the open end for engaging and disengaging at least one pallet.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of Ser. No. 355,684, filedMay 23, 1989, which is a divisional application of Ser. No. 269,473,filed Nov. 9, 1988 and entitled "INTEGRATED BUFFING AND GRINDING SYSTEM"now U.S. Pat. No. 4,930,258.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to a buffing and grindingsystem, more particularly to, a shuttle assembly for an integratedbuffing and grinding system.

2. Description of the Related Art

Presently, articles that are casted, machined or the like may require afinishing process. Typically, the articles may be finely ground againstan abrasive surface such as that of a belt or band-type sanding device.An operator generally grasps the article from a pallet or the like withits hands or a tool and moves the article into and out of contact withthe abrasive surface of the sanding device. Once the grinding iscompleted, the article is transferred to a buffing area or station on apallet or in a batch container. Another operator will generally graspthe article and load it on a moveable table or any type of mechanismthat cooperates with a buffing device at the buffing station. Once thetable is loaded by the operator, the operator will activate, typically,a computer controller that will cause the moveable table to move thearticles into and out of contact with the buffing wheel or wheels of thebuffing device. Once the buffing is completed, the operator unloads thearticles from the moveable table and places them on a pallet.

As to the buffing device, after a large number of articles have beenbuffed, the buffing wheel may need to be tightened and will eventuallyneed to be replaced or repaired. This requires removal of the buffingwheel from the buffing device. Typically, a large nut which is threadedonto a shaft supporting the buffing wheel has to be unloosened andremoved. The buffing wheel is then moved axially until it completelydisengages the shaft.

One disadvantage with the above finishing process is that a large amountof repetitive manual labor is required. This not only results in anexpensive process, but requires a significant amount of inefficientlyallocated human resources. Also, reliance is placed on the operator torepeatedly perform the job correctly for each and every articlesubjected to the finishing process. Another disadvantage with the abovefinishing process is that once the articles have been ground, they aretransferred and loaded manually on the moveable table that cooperateswith the buffing device. A disadvantage of the buffing device is that alarge force has to be applied with a wrench to unloosen or tighten thenut which holds the buffing wheel. This mechanism also requires anunnecessary waste of time to remove and replace the buffing wheel.

It is, therefore, a principle object of the present invention to providea finishing process in which the grinding and buffing process is fullyintegrated.

It is an object of the present invention to provide a system withflexibility such that different articles and finishing processes can beused.

It is another object of the present invention to eliminate orsubstantially reduce the amount of repetitive manual labor required.

It is a further object of the present invention to eliminate orsubstantially reduce the amount of reliance placed on the operator.

It is a still further object of the present invention to provide anautomated finishing system which will consistently grind and buff thearticles to their specified finished dimensions.

It is another object of the present invention to provide a way ofcausing a constant amount of force to be continuously applied to thebuffing wheel.

It is a further object of the present invention to provide a shuttleassembly that may be manually loaded and unloaded.

It is a still further object of the present invention to provide ashuttle assembly which may be a stand-alone device that cooperates witha moveable working table and finishing device.

It is yet another object of the present invention to provide a shuttleassembly that cooperates with a finishing device and eliminates thenecessity of a conveyor.

It is yet still another object of the present invention to provide ashuttle assembly that may be loaded and unloaded with articles while afinishing device is finishing another set of articles.

SUMMARY OF THE INVENTION

The present invention provides a shuttle assembly for supporting atleast one pallet and adapted to cooperate with a moveable working table.The shuttle assembly includes a frame and means on the frame forproviding at least one loading and unloading platform having an open endadapted to allow transfer of at least one pallet between the loading andunloading platform and the moveable working table. The shuttle assemblyalso includes clamping means located opposite the open end for engagingand disengaging at least one pallet.

One advantage of the present invention is that the shuttle assembly maybe used to manually load and unload articles on the pallets. Anotheradvantage of the present invention is that the shuttle assemblycooperates with the moveable working table in a way which will permitseveral articles to be automatically finished at the same time. Yetanother advantage of the present invention is that the shuttle assemblyremoveably locks and unlocks the pallet on the shuttle assembly. A stillfurther advantage of the present invention, is that the shuttle assemblymay be a separate stand-alone device which cooperates with a moveableworking table and finishing device, thereby eliminating the necessity ofa conveyor to transfer articles and pallets to the shuttle assembly. Yetstill a further advantage of the present invention is that the shuttleassembly allows an operator to load and unload articles to and from theshuttle assembly, respectively, while the finishing device is finishinganother set of articles.

Other object, features and advantages of the present invention will bereadily appreciated as the same becomes better understood by referenceto the following description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of an overall schematic of the system according tothe principles of the present invention.

FIG. 2 is a plan view of a first stopping mechanism of the firstconveyor of FIG. 1.

FIG. 3 is an elevational view of the first stopping mechanism of FIG. 2.

FIG. 4 is a plan view of a second stopping mechanism and palletunclamp/locating device of the second conveyor of FIG. 1.

FIG. 5 is a front elevational view of the pallet unclamp/locating deviceof FIG. 4.

FIG. 6 is a front elevational view of the second stopping mechanism ofFIG. 4.

FIG. 7 is a side elevational view of the second stopping mechanism ofFIG. 4.

FIG. 8 is a front elevational view of a second pallet used on the secondconveyor of FIG. 1.

FIG. 9 is a side elevational view of the second pallet of FIG. 8.

FIG. 10 is a plan view partially broken away of the second pallet ofFIG. 8.

FIG. 11 is an elevational view of a limit switch on the first conveyorof FIG. 1.

FIG. 12 is a plan view of the limit switch of FIG. 11.

FIG. 13 is a plan view of a shuttle assembly of FIG. 1.

FIG. 14 is an elevational view of the shuttle assembly of FIG. 13 andthe moveable working table of FIG. 1.

FIG. 15 is a plan view of the buffing device of FIG. 1.

FIG. 16 is a partial plan view of the buffing wheel and quick changeassembly of FIG. 15.

FIG. 17 is a sectional view taken along line 17--17 of FIG. 12.

FIG. 18 is a sectional view taken along line 18--18 of FIG. 16.

FIG. 19 is a plan view of an alternate embodiment of the shuttleassembly of FIGS. 13 and 14 according to the present invention.

FIG. 20 is a side elevational view of the shuttle assembly of FIG. 19.

FIG. 21 is an en enlarged partial plan view of a portion of thestructure illustrated in FIGS. 19 and 20.

FIG. 22 is a sectional view taken along line 22--22 of FIG. 21.

DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

Referring to FIG. 1, an overall schematic diagram of the integratedgrinding and buffing system 10 is shown. It should be appreciated thatthe system 10 could be used for various or multiple finishing processes,e.g. deflashing, deburring, etc. The system 10 includes a firstconveyor, generally indicated at 12, for transporting a series ofobjects, parts or articles to be processed or finished. Each article isloaded on the first conveyor 12 at a loading station, generallyindicated at 14. The first conveyor 12 transports the articles in seriesto a cleaning station, generally indicated at 16, where moisture andforeign particles are removed from the articles with pressurized air.The first conveyor 12 then transports the articles to a finishing orgrinding station, generally indicated at 18.

At the grinding station 18, an individual article is grasped by at leastone of the pair of robots 20 and 22 and removed from the first conveyor12. Each of the robots 20 and 22 then bring the article into contactwith a corresponding abrasive belt grinder or sanding device 24 and 26,respectively, for grinding material from the articles. Once the grindingis completed, the robots 20 and 22 transfer the articles to a secondconveyor, generally indicated at 28. The article travels along thesecond conveyor 28 to a shuttle assembly, generally indicated at 30. Thearticle is transferred by the shuttle assembly 30 to load a moveableworking table, generally indicated at 32. The working table 32cooperates with a buffing device, generally indicated at 34, to buff orpolish the articles. Once the articles are buffed, the working table 32transfers the articles to the shuttle assembly 30 where they areunloaded back onto the second conveyor 28. The articles then travelalong the second conveyor 28 to an unloading station, generallyindicated at 36. The articles are then unloaded from the second conveyor28. The system 10 will now be described in more detail.

Referring again to FIG. 1, the first conveyor 12 is formed in agenerally L-shaped closed loop. However, it should be appreciated thatthe first conveyor 12 could be formed into any suitable closed loopshape. Referring to FIG. 3, the first conveyor 12 generally comprises alow friction first chain 38, preferably of plastic, which slides in arecessed track 40 supported by a first frame, generally indicated at 42.Such a chain as that described is well known in the art and may bepurchased commercially from Rexnord, Mechanical Power Division, 725South Adams, Birmingham, Mich. It should be appreciated that the firstframe 42 could have any suitable shape or structure to support the firstchain 38 and recessed track 40 above a support surface such as thefloor.

Referring once again to FIG. 1, a drive mechanism 44 such as a motorhaving a ball screw and a sprocket or wheel to frictionally engage thefirst chain 38 is used to move the first chain 38 along the recessedtrack 40. The drive mechanism 44 is connected to and controlled by amain electrical control panel 46. An operator electrical control panel47 is purchased purchased purchased connected to an communicates withthe main electrical control panel 46 to activate the drive mechanism 44.It should be appreciated that any suitable drive mechanism may be usedto move or drive the first chain 38 of the first conveyor 12. It shouldalso be appreciated that one skilled in the art could make or purchasethe control circuity for the control panels 46 and 47 which operate thevarious electrically or electronically controlled devices that may bedesired for the system 10.

The first conveyor 12 also includes a rotatable guide 48 at each cornerof its configuration to assist the first chain 38 in moving around thecorner. The rotatable guide 48 generally comprises a circular wheelpivotally supported by the first frame 42 of the first conveyor 12 torotate as the first chain 38 is moved by the drive mechanism 44. Itshould be appreciated that other suitable devices could be used toassist the first chain 38 in moving around generally square corners.

Referring to FIG. 2, a more detailed view of the loading station 14 isshown. At the loading station 14, each article is loaded on a transferfixture or first pallet, generally indicated at 50, which travels alongthe first conveyor 12. The article may be loaded manually by a person orautomatically by robot 49, transfer device or the like. It should beappreciated that the article could be loaded on the first conveyor 12 byany type of device or in any manner.

Referring now to both FIGS. 2 and 3, the first pallet 50 is shown to begenerally rectangular in shape. The pallet 50 also has an outwardlyprotruding track engaging portion 52 at its bottom 54 which is shaped toengage the first chain 38 and slide in the recessed track 40 of thefirst conveyor 12. The track engaging portion 52 is generallyrectangular in shape with arcuate ends and frictionally engages thefirst chain 38 due to the weight of the first pallet 50. The firstpallet 50 is made preferably of plastic and weights approximately one(1) to one and a half (11/2) pounds. The first pallet 50 moves with thefirst chain 38 along the recessed track 40. The first pallet 50 may havea platform 56 having a predetermined shape formed on its upper surface58 to hold the article to be finished (shown in phantom lines in thefigures). It should be appreciated that the first pallet 50 may have anyshape and be made of almost any type of material. It should also beappreciated that the platform 56 can have any predetermined shape tohold and secure the article on the first pallet 50. For example, theplatform 56 may be complimentary in shape to that of the article itsupports.

At the loading station 14 of FIG. 1, a meter or first escapementmechanism is generally indicated at 60. Referring to FIGS. 2 and 3, thefirst escapement mechanism 60 is shown to include a fixture or palletpresence switch or sensor 62 to determine if a first pallet 50 ispresent or adjacent it, and a pair of part or article present switchesor sensors 63 to determine or sense if an article is present on thefirst pallet 50. The first escapement mechanism 60 also includes atleast a pair of pneumatically controlled pallet stopping devices 64 and64a that alternately stop the flow of first pallets 50 along theconveyor 12. The first escapement mechanism 60 also includes a palletlocating device 64b which engages and locates the first pallet 50 onceit is stopped. The sensors 62 and 63 may comprise a photo-electric eyesecured to the first frame 42 by means such as nuts 65 and brackets 66to sense whether a first pallet 50 is present and whether an article ispresent on the first pallet 50. If so, the sensors 62 and 63 send asignal to the main electrical control panel 46 which relays a signal toactuate the pallet locating device 64b.

The pallet stopping devices 64 and 64a and the pallet locating device64b each comprises a cylinder 67 retained and supported by brackets 68at both ends to the first frame 42. The brackets 68 are secured byfasteners 70 to the first frame 42. The cylinder 67 has a piston (notshown) therein and a piston rod 72 having one end connected to thepiston and the other end extending axially outwardly of one end of thecylinder 67. The cylinder 67 is connected to, preferably, a source ofpressurized air (not shown) to move the piston and piston rod 72. Itshould be appreciated, however, that pressurized hydraulic fluid couldbe used. The other end of the piston rod 72 is connected to a platemember 74 and secured between nuts 76 threaded on the end of the pistonrod 72. A pallet engaging or stopping member 78 is generally rectangularin shape and slides in a passageway or track 79 formed between thebrackets 68. The pallet engaging member 78 has one end 80 secured by afastener 82 to the plate member 74. The other end of the pallet engagingmember 78 has inclined portions 84 forming a point 85. The inclinedportions 84 engage corresponding inclined portions 86 on the fourcorners of the first pallet 50 to stop the first pallet 50. The point 85on the pallet locating device 85b engages a "V" shaped pocket 87 in theside of the first pallet 50 to prevent the first pallet 50 from beingcocked or misaligned in the track 40.

When the pallet 50 is restrained by the pallet engaging members 78 and78a of the pallet stopping devices 64 and 64a, respectively, and palletlocating device 64b, the conveyor 12 will, of course, continue to run bysliding under the first pallet 50. When the pallet engaging member 78engages the first pallet 50, a pallet engaged limit switch (nor shown)is triggered to send a signal to the main electrical control panel 46that the first pallet 50 is engaged. It should be appreciated that thepallet stopping and locating devices 64, 64a, and 64b are all similar.It should also be appreciated that any type of conventional limit switchcould be used.

As illustrated in FIG. 2, the first pallet stopping device 64 is locatedon one side of the first conveyor 12 and the second pallet stoppingdevice 64a is located on the same side laterally spaced behind the firstpallet stopping device 64. The pallet locating device 64b is laterallyspaced behind the first pallet stopping device 64 on the other side ofthe first conveyor 12. The main control panel 46 sends a signal toactuate the first stopping device 64 to extend the pallet engagingmember 78 and to actuate the second stopping device 64a to retract itspallet engaging member 78a. The first stopping device 64 stops anincoming first pallet 50. When the pallet presence sensor 62 senses afirst pallet 50 present and the article present sensor 63 senses theabsence of an article on the first pallet 50, a signal from the mainelectrical control panel 46 is sent to a solenoid (not shown) to allowthe pressurized air to the cylinder 67 of the pallet locating device 64bactuates to move the piston, piston rod 72b and pallet engaging member78b to move such that the point 85b is disposed in the pocket 87 of thefirst pallet 50.

After the article is loaded on the first pallet 50 and the robot arm isclear of the first escapement mechanism 60, a signal is sent from themain electrical control panel 46 to the pallet locating device 64b toretract the pallet engaging member 78b. The main electrical controlpanel 46 sends another signal to retract the pallet engaging member 78of the first pallet stopping device 64 and extend the pallet engagingmember 78a of the second pallet stopping device 64a to stop or limit theflow of first pallets 50 along the first conveyor 12. The firstescapement mechanism 60 provides on-line accumulation of the pallets 50while the low-friction first chain 38 continues to slide under the firstpallets 50.

Referring to FIG. 1, a second pallet presence switch or sensor 88 islocated on the first conveyor 12 downstream of the first escapementmechanism 60. The second pallet presence sensor 88 is similar to thefirst pallet presence sensor 62, previously described. If the firstpallets 50 back up on the first conveyor 12 to trigger the second palletpresence sensor 88 for a predetermined time period, the main electricalcontrol panel 46 will prevent the first escapement mechanism 60 at theloading station 14 from releasing first pallets 50 until the secondpallet presence sensor 88 is clear.

The first pallets 50 move along the first conveyor 12 to an articlecleaning or air blow-off station 16. The air blow-off station 16generally comprises a hood or housing supported by the frame 42 of theconveyor 12 about a section of the conveyor 12. At least one air nozzle(not shown) is connected to a source of pressurized air and is mountedwithin the housing and directed at the chain 38. A limit switch,generally indicated at 89 (and shown in FIGS. 11 and 12), is engaged andtripped by the pallet 50, sending a signal to the main electricalcontrol panel 46, which turns on the pressurized air from the air sourcethat flows through the nozzles to blow moisture and any foreignparticles off the articles for a predetermined time period. After thepredetermined time period, if the limit switch 89 is not tripped again,the pressurized air will be turned off. The first pallet 50 then travelsalong the first conveyor 12 to grinding station 18. While the limitswitch 89 shown in FIGS. 11 and 12 is an Allen-Bradley limit switch,other suitable switches may be employed in the appropriate application.

At the grinding station 18, at least one, preferably a pair of robotpickup stations, generally indicated at 90 and 90a, are located adjacenta section of the first conveyor 12. A pair robots 20 and 22 are locatedadjacent the robot pickup stations 90 and 90a, respectively. Such arobot 20 and 22 could be a GMF Model S-100R robot which may be purchasedcommercially from GMF Robotics, 2000 South Adams Road, Auburn Hills,Mich. It should be understood that a variety of different robots may beutilized for the system 10, and that these particular robots have beenidentified for exemplary purposes only. It should also be appreciatedthat each of the robots will be controlled by a computer (not shown)which communicates with the main electrical control panel 46. Each robot20 and 21 also has an article presence switch or sensor (not shown) onits arm. Further, belt or band-type grinders 24 and 26 are locatedlaterally of the robots 20 and 22, respectively. Such a band-typegrinder or polisher is a ABH4 grinder which is conventional and may bepurchased commercially from ACME Manufacturing Company, 650 West TwelveMile Road, Madison Heights, Mich. Each grinder 24 and 26 also has anarticle presence switch or sensor (not shown). While grinders are shownas part of an initial finishing station in the system 10, other suitablefinishing devices may be employed in the appropriate application.

At each robot pickup station 90 and 90a, an escapement mechanism,similar to the first escapement mechanism 60, previously described, isalso located. The first escapement mechanism 60 at the first robotpickup station 90 is sequentially controlled to either stop the firstpallet 50 or let it go through to the second robot pickup station 90a.It should be appreciated that either robot 20 or 22 can "work" or beoperated and the first stopping mechanisms 60 sequenced such that eachrobot 20 and 22 receives a first pallet 50 having an article on it.

At the first robot pickup station 90, the first escapement mechanism 60operates similar to the first escapement mechanism 60 at the loadingstation 14. Once a first pallet 50 is stopped and engaged, the firstrobot 20 has an end effector or hand which is connected to a source forcreating a suction or vacuum to pick up the article and hold it. Thefirst robot 20 is actuated to move the article off the first pallet 50to the first grinder 24. Once the first robot 20 has picked up thearticle, the article present switch on the end of its arm will confirmthat this has occurred. The first robot 20 will then sequentially movethe article into and out of contact or engagement with the abrasivesurface of the first grinder 24 to grind or polish the article topredetermined dimensions. When the first robot 20 is finished grindingthe article, the first robot 20 will place it on a locking fixture orsecond pallet, generally indicated at 91 (FIGS. 8 through 10), which issupported on the second conveyor 28. The article is blown out of thehand of the first robot 20 by pressurized air connected to it. It shouldbe appreciated that the second robot 22 operates substantially the sameas the first robot 20 to remove the article, grind it, and place it onone of the second pallets 91 of the second conveyor 28.

Once the arm of the first robot 20 is clear of the first escapementmechanism 60 at the first robot pickup station 90, a signal is given bythe main electrical control panel 46 to the first escapement mechanism60 to release the emptied first pallet 50. A pair of laterally spacedpallet presence sensors 92 and 93 are located along the first conveyor12 between the first 90 and second 90a robot pickup stations. If firstpallets 50 backup on the first conveyor 12 to trigger the palletpresence sensor 92, the first escapement mechanism 60 at the first robotpickup station 90 will be prevented by the main electrical control panel46 from releasing any first pallets 50 until sensor 92 is clear. Also,if the pallet presence sensor 92 is not triggered, the main electricalcontrol panel 46 will cycle the first escapement mechanism 60 at thefirst robot pickup station 90 until the sensor 92 is triggered. Itshould be appreciated that empty pallets from the robot pickup stations90 and 90a are conveyed back to the loading station 14.

Referring to FIG. 1, the second conveyor 28 is formed in a generallyrectangular shaped closed loop. The second conveyor 28 comprises twoseparate closed loop second chains 94 and 95 which act as one closedloop chain. It should be appreciated that the second conveyor 28 couldbe formed to any desired shape and could have a single closed loopchain. However, two chains are preferred due to the weight of the secondpallets 91. Each second chain 94 and 95 has its own corresponding drivemechanism 96 and 97 similar to that of the first conveyor 12. Such aconveyor may be purchased commercially from Rexnord, Mechanical PowerDivision, 725 South Adams, Birmingham, Mich.

Referring to FIG. 5, the second conveyor 28 includes the low frictionsecond chains 94 and 95 which are generally planar and has a downwardlyprotruding portion 98 on its bottom surface 99 which slides in a channelor track 100 supported by a second frame, generally indicated at 102.The second frame 102 includes a generally rectangular tubular member104. The tubular member 104 supports stacked plate members 106 and 108which form the track 100 for the second chains 94 and 95. The secondchains 94 and 95 slide along the track 100 and return inverted throughthe tubular member 104. It should be appreciated that the second frame102 could have any shape or structure to support the second chain abovea support surface such as the floor.

The second pallet 91 supports the article and frictionally engages thesecond chains 94 and 95 due to its weight and travels along the secondconveyor 28. The second pallet 91 is preferably made of metal and weighsapproximately twenty-five (25) pounds. It should be appreciated,however, that the second pallet 91 could be made of any type of materialto support the article during the second finishing operation to bediscussed below.

Referring to FIGS. 8 through 10, the second pallet 91 comprises a basemember 110 which engages chains 94 and 95 and moves along the track 100,a pair of spaced upright or vertical support members 112 and 114connected at one end to the base member 110 and a top plate member 116connected at the other end of the support members 112 and 114. Thesupport members 112 and 114 are secured to the base member 110 by weldsand the top plate member 116 is secured to the support members 112 and114 by fasteners 118. The base member 110 also has a pair of spacedupright flanges 119 along one side. The second pallet 90 furtherincludes a plurality of platform members 120, 122, 124, 126 extendingupwardly from the top plate member 116. These platform members are usedto define a predetermined shape which is capable of supporting thearticle as shown by phantom lines in the figure. It should beappreciated that the second pallet 91 may have a platform of anypredetermined shape on the upper surface of the top plate member 116which is capable of holding and supporting the article to be finished.Thus, for example, the platform members 120-126 define a contouredsurface which is generally complementary in shape to the underside shapeof the article to be finished.

The second pallet 91 further includes a unique locking arrangement,generally indicated at 130 to removably secure the article to the secondpallet 90. The locking arrangement 130 includes a lever arm 132pivotally supported by a fastener 134. The fastener 134 is enclosed by abushing 136 which extends through an aperture 138 in the lever arm 132.The fastener 134 threadably engages platform member 124 and is securedthereto. As illustrated in FIG. 9, the lever arm 132 includes anL-shaped ketch member 140 at one end which cooperates with the uppersurface 142 of platform member 124 to removably secure the articletherebetween. The ketch member 140 is secured to the lever arm 132 by aplurality of fasteners 144.

The lever arm 132 is actuated by a push rod 146 at its lower end. Thepush rod 146 is generally circular and located planar to the base member110. The push rod 146 has an aperture 148 formed in it and the lower endof the lever arm 132 is spherically shaped and disposed in the aperture148. The push rod 146 has one end disposed in a bushing 150 press-fitinto a corresponding aperture 152 formed in the vertical support member114, such that the push rod extends outwardly of the vertical supportmember 114. The other end of the push rod 146 is disposed in a bushing154 press-fitted in a corresponding aperture 156 formed in the verticalsupport member 112. The push rod 146 includes a shoulder 158 formedthereon. A washer 160 abuts the shoulder 158 and another washer 162abuts the vertical support member 112. A spring 164 is disposed aboutthe push rod 146 between washers 160 and 162 to bias the push rod 136such that the ketch member 140 engages or contacts the surfaces 142 ofthe form member 124. A first fastener 166 threadably engages thevertical support member 114 to limit the movement of the lever arm 132and the preload on the article. A second fastener 168 threadably engagesthe vertical support member 112 to limit the movement of the lever arm132 toward the vertical support member 112.

Referring to FIG. 1, across from each robot 20 and 22, a secondescapement mechanism, generally indicated at 170, is located along thesecond conveyor 28 to stop a second pallet 91 until it is loaded with anarticle that has been processed or finished by the robots 20, 22.Referring to FIGS. 4 and 5, the second escapement mechanism 170 includesa pallet presence sensor 170 and a pair of article present sensors 172similar to the pallet presence sensor 62 and article present sensor 63of the first escapement mechanism 60. The pallet presence sensor 171secured by nuts 173 to L-shaped bracket 174 which is, in turn, securedby fasteners 175 to the second frame 102. The pallet presence sensor 171determines or senses whether a second pallet 91 is present. The secondescapement mechanism 170 also includes a pair of article present sensors172 each located on opposite sides of the second chain 94, 95 todetermine or sense whether an article is present on the second pallet91. The article present sensors 172 are secured by nuts 176 to L-shapedbracket members 177 which are, in turn, secured by fasteners 178 to thesecond frame 102.

Referring to FIGS. 4, 6 and 7, the second escapement mechanism 170includes a pair of laterally spaced and generally U-shaped bars 179 and179a having inwardly extending pallet engaging flanges 180 and 180a atthe free end. The U-shaped bars 179 and 179a are guided in their up anddown movement by guide bearings 181 secured to the second frame 102. Thebars 179 and 179a are connected to a corresponding piston rod 182 of apneumatic cylinder 183 to move the bars 179 and 179a up and downrelative to the chain 94, 95. The pneumatic cylinders 183 and 183a areretained by brackets 184 to the second frame 102 and the brackets 184are secured to the frame 102 by fasteners 185. The pneumatic cylinders183 and 183a are sequentially controlled by the main electrical controlpanel 46 to stop a second pallet 91 by a first bar 179 engaging the basemember 110 of the second pallet 91.

Referring to FIGS. 4 and 5, a pallet unclamp/locating device 186 islocated at each second escapement mechanism 170 on the second conveyor28 across from the robots 20 and 22. The pallet unclamp/locating device186 includes a cylinder 187 retained by brackets 188 to the second frame102. The brackets 188 are secured by fasteners 190 to the second frame102. The cylinder 187 has a piston (not shown) therein and a piston rod192 connected to the piston and extending axially outwardly of one endof the cylinder 187. The cylinder 187 is connected to a source ofpressurized air (not shown) to move the piston and piston rod 192axially. A push block 194 is connected to the other end of the pistonrod 192. The push block 194 has a projection 195 conforming to the shapeof the end of the push rod 146 for cooperating with the push rod 146.When the piston rod 192 is extended, the push block 194 engages the pushrod 146 and displaces the lever arm 132, in turn, disengaging the ketchmember 140 from the article. When the piston rod 192 is retracted, thepush block 194 disengages the push rod 146 and the lever arm 132 returnsto its original position with the ketch member 140 engaging the article.It should be appreciated that a second escapement mechanism 170 and apallet unclamp/locating device 186 is located along the second conveyor28 across from the second robot 22 and operates similar to thatpreviously described.

If a second pallet 91 is detected with no article on it by the articlepresent sensors 172, the main electrical control panel 46 will signalthe pallet unclamp/locating device 186 to engage the second pallet 91.After the pallet unclamp/locating device 186 has engaged the secondpallet 91 and triggered a limit switch (not shown), the first robot 20will receive a signal from the main electrical control panel 46 to loadthe second pallet 91. Once this occurs as confirmed by the articlepresent sensors 171 and the arm of the robot 20 is clear of the secondescapement mechanism 170, the main electrical control panel 46 will givea signal to the pallet unclamp/locating device 186 to disengage thesecond pallet 91. The main electrical control panel 46 then givesanother signal to the second escapement mechanism 170 to actuate andrelease the second pallet 91. It should be appreciated that theoperation is the same for the second escapement mechanism 170 and palletunclamp/locating device 186 across from the second robot 22.

Between the second escapement mechanism 170 across from the first 20 andsecond 22 robots, a pallet presence sensor 198 is located. The palletpresence sensor 198 is similar to the pallet presence sensor 171. In theevent that the first robot 20 is not operating, the second escapementmechanism 170 across from the first robot 20 will only release secondpallets 91 when the pallet presence sensor 198 is not triggered. In theevent that the second robot 22 is not operating, second pallets 91 willback-up to trigger pallet presence sensor 198, preventing the secondescapement mechanism 170 across from the first robot 20 from releasingsecond pallets 91. The pallet presence sensor 171 will turn ON a warninglight at an operator electrical control panel 47 which communicates withthe main electrical control panel 46. If the operator wishes to continuethe operation, it must activate a manual override switch (not shown)that will allow the second escapement mechanism 170 across from thefirst robot 20 to pass second pallets 91 through it. Once the secondpallet 91 is released, the second pallet 91 travels along the secondconveyor 28 to a second escapement mechanism 170 a adjacent the entry ofthe shuttle assembly 30.

The second escapement mechanism 170a controls the feed to shuttleassembly 30. The second escapement mechanism 170a will allow secondpallets 91 with articles on them to pass through until the shuttleassembly 30 is fully loaded. Second pallets 91 that do not contain anarticle will be stopped by the second escapement mechanism 170a whichwill, in turn, activate or turn ON a light at the operator electricalcontrol panel 47 to indicate that a second pallet 91 is without anarticle. The main electrical control panel 46 will shut down the secondescapement mechanism 170a. The operator must purge the shuttle assembly30 and reset the second escapement mechanism 170a in a manner to bedescribed.

At the shuttle assembly 30, a plurality of shot bolts or third palletstopping devices, generally indicated at 200, are located and spacedalong a work station section of the second conveyor 28. Preferably, fiveof the third pallet stopping devices 200 are used. However, it should beappreciated that the number of stopping devices 200 will depend upon theparticular application of the system 10. Each of the third palletstopping devices 200 is similar to the pallet stopping devices of thesecond escapement mechanism 170. Each third pallet stopping device 200has one U-shaped bar 202 that moves up above the plane of the secondchain 94 to engage and stop the second pallet 91 and down below theplane of the chain to disengage and allow the second pallets 91 to passby it. The bar 202 is connected to a piston rod (not shown) of apneumatic cylinder (not shown) secured to the second frame 102. Whenfive of the second pallets 91 have been sequentially stopped, theshuttle assembly 30 moves the five second pallets 91 in unison to aloading position to be described. It should be appreciated thatcorresponding limit switches are used with the third stop mechanisms 200to monitor the movements of the bar 202.

Referring to FIGS. 13 and 14, the shuttle assembly 30 is shown. Theshuttle assembly 30 includes a secondary support frame, generallyindicated at 210, mounted on the upper surface 212 of the second frame102. The secondary support frame 210 comprises a plurality oflongitudinally and laterally spaced vertical support columns 214supported upon a pair of laterally extending and longitudinally spacedsupport beams 216. The support beams 216 are secured to the second frame102 by means such as welds 217. A plate member 218 is secured to theupper ends of a pair of support columns 214. In this particularembodiment, a total of three plate members 218 are used. Upon the centerplate member 218, a drive cylinder 220 is retained by brackets 222 tothe plate member 218. The brackets 222 are secured by fasteners 224 tothe plate member 218. The drive cylinder 220 includes a piston (notshown) slideably disposed therein for reciprocal movement. A source ofpressurized air is connected to the drive cylinder 220 to move thepiston. A piston rod 226 is connected to one end of the piston andextends axially outwardly from one end of the drive cylinder 220. AnL-shaped member 228 is secured to the other end of the piston rod 226.The horizontal portion of the L-shaped member 228 is secured by meanssuch as fasteners 230 to a horizontal drive bar 232. The drive bar 232extends laterally along a section of the second conveyor 28. A contactbar 233 extends downwardly from the free end of the drive bar 232 tocontact the base member 110 of the second pallets 91. The drive cylinder220 pushes and pulls the drive bar 232 to move the second pallet 91 backand forth across the second conveyor 28. It should be appreciated thatcorresponding limit switches are used with the drive cylinder 220 tomonitor the movements of the drive bar 232.

Upon the end or other two plate members 218, a guide assembly, generallyindicated at 234, is mounted. The guide assembly 234 includes a pair oflongitudinally spaced bearing blocks 236 secured by means such asfasteners 238 to the corresponding plate member 218. The bearing blocks236 have an aperture (not shown) communicating axially through them. Aguide rod 240 is disposed in the apertures and has one end connected toa corresponding L-shaped member 228, previously described. The L-shapedmember 228 is secured by means such as fasteners 230 to the drive bar232. The guide assemblies 234 guide or maintain alignment of the drivebar 232 substantially parallel to the track 100 as it is moved by thedrive cylinder 220.

Across the second conveyor 28 from the drive bar 232, a plurality ofL-shaped support angles 242 are secured to the second frame 102. A pairof longitudinally spaced and laterally extending support rails 244 aresecured to the horizontal portion of the support angles 242. A pluralityof longitudinally extending skid rails 246 are secured to the supportrails 244. The skid rails 246 are spaced along the support rails 244 toform a plurality of loading (dotted lines) and unloading (phantom lines)stations for guiding the movement of the second pallets 91 as shown inFIG. 13. The number of loading and unloading stations formed should, ofcourse, correspond to the number of stopping locations on the conveyor28 at this work station (i.e., 5). The skid rails 246 support and guidethe second pallets 91. A laterally extending keeper bar 248 with a pairof limit switches (not shown) are disposed between the second chain 90of the second conveyor 28 and one end of the skid rails 246. The keeperbar 248 is connected to and supported by a piston rod 250 (partiallyshown) of a pair of pneumatic cylinders (not shown), previouslydescribed, at its ends which are secured to the second frame 102. Thecylinders move the keeper bar 248 up and down to allow or prevent thedrive bar 232 from moving the second pallets 91 to the loading positionsand the unloading positions on the skid rails 246. In other words, thekeeper bar 248 forms a moveable wall on one side of the conveyor 28.

As illustrated in FIG. 14, a pallet presence sensor 252 is supported byan L-shaped bracket 254 which is secured by means such as a fastener 256to the second frame 102. The pallet presence sensor 252 is located beloweach loading station of the shuttle assembly 30 adjacent each thirdpallet stopping device 200. The pallet presence sensor 252 is similar tothe pallet presence sensors previously described. When the palletpresence sensor 252 detects or senses a second pallet 91, it sends asignal to the main electrical control panel 46, which relays a signal toactuate the appropriate third pallet stopping device 200.

A terminal clear sensor 258 is secured by nuts 260 to a horizontal platemember 262 which is supported above the unload stations of the shuttleassembly 30 by a post 264. The post 264 may be secured to the supportrails 244 by means such as welds. The terminal clear sensors 258 aresimilar to the pallet presence sensors 252 and detect or sense whether asecond pallet 91 is present in the unloading stations. When the terminalclear sensors 258 sense the presence of second pallets 91 in theunloading stations, they send a signal to the main electrical controlpanel 46, which relays a signal to actuate the keeper bar 248.

Correspondingly, a clamp assembly, generally indicated at 266, ismounted to the drive bar across from each unloading station. The clampassembly 266 includes a C-shaped clamp member 268 having downwardlyextending fingers 270 at the ends which engage and disengage the uprightflanges 119 of the base member 110 on the second pallet 91. The clampmember 268 is pivotally supported by a shaft 272 between a pair oflaterally spaced side members 274. A pneumatic cylinder 276 having anaxially extending piston rod 278 is connected to each clamp member 268to pivot it between an engaged and disengaged position with the basemember 110 of the second pallet 91.

Referring to FIG. 14, a multiple-axis moveable or working table 32 islocated across from the shuttle assembly 30 and operatively cooperateswith the shuttle assembly 30 to transfer the second pallets 91 in theloading position to a buffing mechanism 34 (FIG. 15). The working table32 is a multiple-axis or RT5 work table which may be purchasedcommercially from ACME Manufacturing Company, 650 West Twelve Mile Road,Madison Heights, Mich. The working table 32 includes a base 280 havingrollers 281 which translate along a pair of rails 282 for longitudinalmovement. The working table 32 includes a work spindle support 283having rollers 284 which translate along a pair of rails 285 connectedto the base 280 for lateral movement.

The working table 32 further includes five work spindles, generallyindicated at 286, that have a clockwise and counter-clockwise rotationwith synchronized movement. The work spindle 286 includes at least one,preferably a plurality of, plate members 287 on which the base member110 of the second pallet 91 rests and is supported. The work spindle 286further includes a pair of laterally spaced U-shaped clamps 288 whichmove vertically up and down to engage and disengage the second pallet91. The work spindle 286 includes a cylinder (not shown) has a piston(not shown) and a rod 289 with one end connected to the piston. Theother end of the rod 289 is connected to clamps 288. The cylinder isconnected to either a source of pressurized air or hydraulic fluid tomove the rod 289 and clamps 287 up and down to engage and disengage thebase member 110 of the second pallet 91. It should be appreciated thateach work spindle 286 has its own high torque anti-backlash gear boxwith an "X" axis range of 42", "Y" axis range of 12", and a "Z" axiswith 360° spindle rotation. It should also be appreciated that tablemovements are facilitated by use of ball screws and guide rails, poweredby servo motors and encoder feedback. It should further be appreciatedthat the working table 32 uses a micro computer system which allows apoint to point or continuous path control.

The working table 32 moves the second pallets 91 from the shuttleassembly 30 into and out of contact with the buffing wheel 306 (FIG. 15)of the buffing mechanism 34 to buff the articles. Once the buffing iscompleted, the working table 32 transfers the second pallets 91 to theunloading position or stations on the shuttle assembly 30.

Referring to FIG. 15, a plan view of the buffing mechanism 34 is shown.The buffing mechanism 34 includes a support frame, generally indicatedat 290. The support frame 290 includes a pair of vertical columns 292 toallow other portions of the support frame 290 to translate up and downalong the columns 292. The support frame 290 also journally supports arotatable primary shaft 294 between two end supports 296 and 298 of thesupport frame 290. The end support 298 is secured to the rest of thesupport frame 290 by means of fastener 299. The primary shaft 294 isgenerally cylindrical in shape and is also supported by a bearing 300between a pair of support members 301 connected to the rest of thesupport frame 290. The bearing 300 and support members 301 support theprimary shaft 294 in a cantilevered manner when end support 298 isremoved or swung out of the way. The primary shaft 294 also has aplurality of pulleys 302 at one end. The primary shaft 294 also has anenlarged diameter area 303 along a section of its length to support aplurality of flexible buffing discs 304 which make up a buffing wheel,generally indicated at 306. A plurality of nozzles 308 are supported bylaterally extending support members 310 connected to the rest of supportframe 290. A source of abrasive material (not shown) and pressurized airare supplied through conduits 311 and 312 and are connected to thenozzles 308. The abrasive material and air mixture is discharged fromthe nozzles 308 to cooperate with the buffing wheel 306 to buff orpolish the articles.

A secondary shaft 314 is also supported by the support frame 290 andspaced from the primary shaft 294. The secondary shaft 314 also includesa plurality of pulleys 316 at one end and in alignment with the firstpulleys 302 of the primary shaft 294. A plurality of "V" shaped belts318 interconnect the first 302 and second 316 pulleys. The secondaryshaft 314 also includes a plurality of third pulleys 320 at its otherend. A variable speed drive motor 322 having a rotating shaft 324 isalso supported by the support frame 290 and spaced longitudinally fromthe secondary shaft 314. A plurality of fourth pulleys 326 are connectedto one end of the shaft 324 of the drive motor 322 and are in alignmentwith the third pulleys 320 of the secondary shaft 314. A plurality of"V" shaped belts 328 interconnect the third 320 and fourth 326 pulleys.The drive motor 322 is connected to and controlled by the mainelectrical control panel 46.

In operation, electrical power to the drive motor 322 rotates its shaft324 and the fourth pulleys 326. As the fourth pulleys 326 rotate, thebelts 328 rotate, in turn, rotating the third pulleys 320, secondaryshaft 314 and second pulleys 316. As the second pulleys 316 rotate, thefirst belts 318 rotate, in turn, rotating the first pulley 302, primaryshaft 294 and buffing wheel 306. It should be appreciated that any typeof drive train or mechanism can be used to rotate the primary shaft 294and buffing wheel 306. It should also be appreciated that the air andabrasive mixture can be controlled by the main electrical control panel46 to the discharged at predetermined times.

Referring to FIGS. 16 through 18, a quick change assembly, generallyindicated at 330, of the present invention for removing the buffingdiscs or wheel 306 is shown. A first plate member 332 is disposed aboutthe primary shaft 294 near one end of the enlarged diameter portion 303.A moveable second plate 334 is disposed laterally from the first plate332 about the enlarged diameter portion 303 of the primary shaft 294.The buffing discs 304 are disposed adjacent one another and aresupported on the enlarged diameter portion 303 of the primary shaft 294between the first 332 and second 334 plates.

Referring to FIGS. 16 and 18, a plurality, and preferably three,cylinder assemblies, generally indicated at 336, are connected to theprimary shaft 294. The cylinder assemblies 336 each comprise a cylinder338 having a piston (not shown) disposed therein for axial movement. Apiston rod 340 has a first end connected to the piston and a second endextending axially outwardly from the cylinder 338 and connected to thesecond plate 334. The cylinder assemblies 336 include bracket members342 disposed about the cylinders 338 and secured by means such asfasteners 344 to the primary shaft 294. The cylinder assemblies 336 areequally spaced circumferentially about the primary shaft 294. A rotarycoupling 347 is disposed at the end of the primary shaft 294. Thecylinder assemblies 336, preferably, have a source of pressurized airconnected to them by conduits (not shown) which extend through apassageway 346 in the primary shaft 294 and are connected to the rotarycoupling 347. It should be appreciated that hydraulic fluid could beused to actuate the cylinder assemblies 336. The cylinder assemblies 336rotate with the primary shaft 294 and are actuated such as to extend orretract the second plate 334 axially along the primary shaft 294. Aflexible housing 348 is disposed about the cylinder assemblies 336 toprevent foreign matter from contacting them.

Referring to FIG. 17, the first plate 332 is generally circular andincludes a generally circular aperture 350 communicating axiallytherethrough. The first plate 332 includes a plurality of generallyrectangular pockets 352 extending radially outwardly from the circularaperture 350 formed in the first plate 332. Preferably, six pockets 352are formed in the first plate 332 and spaced substantially equallycircumferentially about the aperture 350 of the first plate 332.Preferably, only three of the pockets 352 communicate through the firstplate 332. The other three pockets 352a are recessed in the first plate332 and have a flange portion 353 between the sides of the pockets 352a.The enlarged section 302 of the primary shaft includes a plurality ofcircumferentially spaced keeper members 354. Preferably, three keys orkeeper members 354 are spaced substantially equally circumferentiallyabout and secured to the primary shaft 294 by means such as welds 356.The sloping portions 358 of the keeper members 354 are generallyrectangular and have an inclined or sloping portion 358 at one end whichacts as a guide. The keeper members 354 cooperate with the pockets 352of the first plate 332 to guide the first plate 332 onto the primaryshaft 294. Once the first plate 332 is moved to a slot 360 in the keepermembers 354, the first plate 332 is rotated such that the flangeportions 353 between the pockets 352a are about the ends of the keepermembers 354.

To remove the buffing wheel 306, pressurized air or hydraulic fluid tothe cylinder assemblies 336 is discontinued. As a result, the compressedbuffing discs 304 expand to move the second plate 334 away from thefirst plate 332. The end support 298 of the support frame 290 is swungout of the way by unsecuring fastener 299 to disengage the end of theprimary shaft 294. The first plate 332 is then pushed toward the buffingwheel 306 and rotated such that the pockets 352 become aligned with thekeeper members 354. The first plate 332 is moved axially to disengagethe first plate 332 from the primary shaft 294. Each of the discs 304 ofthe buffing wheel 306 are then slid axially off the primary shaft 294.

Once the buffing wheel 306 has been replaced, the pockets 352 of thefirst plate 332 are aligned with the keeper members 354 and the firstplate 332 is moved axially onto the primary shaft 294 to the slot 360past the ends of the keeper members 354. The first plate 332 is thenmanually rotated to align the flange portions 353 with the ends of thekeeper members 354. Once this is accomplished, pressurized air isprovided to the cylinder assemblies 336, thereby causing the piston rod340 to rapidly move the second plate 334. The second plate 334compresses the buffing discs 304 toward the first plate 332 to securethem therebetween.

Referring to FIG. 1, once the second pallets 91 are unloaded by theworking table 32 on the unloading stations of the shuttle assembly 30,the pallet presence sensors 258 send a signal to the main electricalcontrol panel 46. The main electrical control panel 46 sends a signal toactuate the cylinders to lower the keeper bar 248. The clamp assemblies266 are actuated by the main electrical control panel to engage theflanges 119 on the base member 110 of the second pallets 91. The mainelectrical control panel 46 sends a signal to the drive cylinder 220 toretract the piston rod 226, drive bar 232 and second pallets 91. Uponthe second pallets 91 arriving at the retracted position, a signal froma limit switch (not shown) is sent to panel 46 which relays a signal toactuate the cylinders to raise the keeper bar 248. Once this isaccomplished, another limit switch (not shown) signals the panel 46which relays a signal for the clamp assemblies 266 to disengage theflanges 119 on the base member 110 of the second pallets 91, allowingthe second pallets 91 with finished articles to be conveyed to theunloading station 36.

At the unloading station 36, a second escapement mechanism 170,previously described, is located along the conveyor 28. A palletpresence sensor 172 will send a signal to the panel 46 which a relays asignal to unclamp the second pallet 91. The unclamp/locating device 186will engage the second pallet 91 and unclamp the ketch member 140 fromthe article. Preferably, the operator will manually remove the articlefrom the second pallet 91. The operator will release a foot pedal 370signaling the unclamp/locating device 186 to retract or disengage thesecond pallet 91. Once this occurs, the panel 46 will actuate the secondescapement mechanism 170, releasing the second pallet 91 and allowing itto be conveyed to the second escapement mechanism 170 across from thefirst robot 20. After a predetermined time delay, the second escapementmechanism 170 will cycle, allowing a second pallet 91 to enter theunloading station 36. It should be appreciated that the unloadingstation 36 could be fully automated for unloading the articles from thesecond pallets 91.

IN OPERATION

Referring to FIG. 1, the articles are loaded by a robot 49 or the likeat the loading station 14. A first pallet 50 traveling along the firstconveyor 12 is stopped by the first escapement mechanism 60. At thefirst escapement mechanism 60, two switches or sensors, a fixture orpallet presence switch or sensor 62 and a part or article present switchor sensor 63 sense whether a first pallet 50 is present and if there isan article on the first pallet 50. If there is no article on the firstpallet 50, the first pallet 50 is held by the pallet stopping device 64and a signal is given by the main electrical control panel 46 to thepallet locating device 64b to engage the first pallet 50. After thefirst pallet 50 is engaged and the pallet engaged switch (not shown) istriggered, a signal is given by the main electrical control panel 46 tothe robot 49 to load an article onto the first pallet 50. Once thearticle is loaded on the first pallet 50 and the robot 49 signals thatits arm is clear of the first escapement mechanism 60, a signal is givenby the main electrical control panel 46 to retract or disengage thepallet locating device 64b. Another signal is then given by the mainelectrical control panel 46 to the first escapement mechanism 60 toretract the first pallet stopping device 64 to release the first pallet50 and extend the second pallet stopping device 64a to stop anotherfirst pallet 50. After a predetermined time delay, a signal is given tothe first escapement mechanism 60 to extend the first pallet stoppingdevice 64 and retract the second pallet stopping device 64 and retractthe second pallet stopping device 64a to load another first pallet 50onto the loading station 14. If a plurality of first pallets 50 back upon the first conveyor 12 to trigger the second pallet presence sensor88, the first escapement mechanism 60 at the loading station will notrelease any first pallets 50 until the second pallet presence sensor 88is clear.

The first pallets 50 travel along the first conveyor 12 to the cleaningor air blow-off station 16. The first pallet 50 will trigger a limitswitch 89 which turns on pressurized air from an air source which flowsthrough the nozzles in the housing. The pressurized air will blow-offany moisture or foreign articles passing through the housing. If thelimit switch 89 is not triggered again by another first pallet 50, atime delay will turn off the pressurized air.

The first pallet 50 with the article on it is conveyed from the airblow-off station 16 to the first robot pickup station 90 of the grindingstation 18. A first escapement mechanism 60 at the first robot pickupstation 90 includes a pallet presence sensor 62 to sense whether a firstpallet 50 is present and an article present sensor 63 to sense whetherthere is an article on the first pallet 50. If an article is present onthe first pallet 50, a signal will be given to trigger the palletlocating device 64b to engage the first pallet 50. After the firstpallet 50 is engaged and the pallet engaged limit switch (not shown) istriggered, the first robot 20 will pick up the article from the firstpallet 50. Once the first robot 20 has picked up the part and it isconfirmed by the article present switch on the end of the robot arm, thefirst robot 20 will present the article to the first belt grinder 24 andperform the grinding operation.

Once the first robot 20 signals that its arm is clear of the firstescapement mechanism 60, a signal is given to return the pallet locatingdevice 64b. Another signal is given to the first escapement mechanism 60to release the first pallet 50. After a predetermined time delay, asignal is given to the first escapement mechanism 60 to load anotherfirst pallet 50 into the first robot pickup station 90. The firstescapement mechanism 60 is configured to normally fire twice each cycle,thereby releasing one emptied first pallet 50 and one full first pallet50 to be conveyed to the second robot pickup station 90a for pickup bythe second robot 22. If the first pallets 50 backup for any reason onthe first conveyor 12 and trigger the pallet presence sensor 92, thefirst escapement mechanism 60 at the first robot pickup station 90 willnot release first pallets 50 until the sensor 92 is clear. It should beappreciated that if the pallet presence sensor 93 is not triggered, thefirst escapement mechanism 60 at the first robot pickup station 90 willcycle until this sensor 93 is triggered.

The second robot 22 at the second robot pickup station 90a will normallyreceive articles on every other first pallet 50. A first escapementmechanism 60 is located at the second robot pickup station 90a andoperates similar to the first escapement mechanism 60 at the first robotpickup station 90. It should be appreciated that if no article is on thefirst pallet 50 at the second robot pickup station 90a, the stoppingmechanism 60 will receive a signal to release the first pallet 50. Emptyfirst pallets 50 from both the first 90 and second 90a robot pickupstations are conveyed back to the loading station 14. It should beappreciated that if the first robot 20 is not operating, the firstescapement mechanism 60 at the first robot pickup station 90 will fireor cycle as long as the pallet presence sensor 92 is not triggered. Itshould also be appreciated that if the second robot 22 is not operating,first pallets 50 will back up to the pallet presence sensor 92, causingthe first escapement mechanism 60 at the first robot pickup station 90to start releasing first pallets 50 regardless if the first pallet 50has an article on it. It should be further appreciated that the firstescapement mechanism 60 at the first robot pickup station 90 will onlyrelease empty first pallets 50 when the pallet presence sensor 92 is nottriggered.

Once the articles have been completed at the grinding station 18, therobots 20 and 22 will load them onto empty locking or second pallets onthe second conveyor 28. A second escapement mechanism 170 is locatedalong the second conveyor 28 across from the first robot 20. The secondescapement mechanism 170 includes a pallet presence sensor 171, anarticle present sensor 172 and a pallet unclamp/locating device 186. Thepallet presence sensor 171 senses whether a second pallet 91 is presentand an article present sensor 172 senses whether there is an article onthe second pallet 91. If a second pallet 91 is present with an articleon it, a signal to the second escapement mechanism 170 will release thesecond pallet 91. After a predetermined time delay, a signal is given bythe main electrical control panel 46 to second escapement mechanism 170to load another second pallet 91 into the second escapement mechanism170 across from the first robot 20.

If a second pallet 91 is present with no article on it, a signal will begiven by panel 46 to the pallet unclamp/locating device 186 to engagethe second pallet 91. After the pallet unclamp/locating device 186 hasengaged the second pallet 91 and a limit switch (not shown) triggered,the first robot 20 will receive a signal to load an article onto thesecond pallet 91. Once the first robot 20 has loaded an article onto thesecond pallet 91 and the first robot 20 signals that its arm is clear,it is confirmed by the pallet presence sensor. A signal is given by themain electrical control panel 46 to return the pallet locating/unclampdevice 186. Another signal is given by the main electrical control panel46 to the second escapement mechanism 170 across from the first robot 20to release the second pallet 91. After a predetermined time delay, asignal is given by the main electrical control panel 46 to the secondescapement mechanism 170 to load another second pallet 91 into thesecond escapement mechanism 170 across from the first robot 20. Itshould be appreciated that in order for the second robot 22 not to bestarved for articles, if the pallet presence sensors and article presentsensors are triggered, the pallet unclamp/locating device 186 will notfunction and the second escapement mechanism 170 across from the firstrobot 20 will release a second pallet 91. It should also be appreciatedthat the second escapement mechanism 170 across from the first robot 20is configured to normally fire twice each cycle, thereby releasing onefull second pallet 91 and one empty second pallet 91 each full cycle.

Another second escapement mechanism 170 is located along the secondconveyor 28 across from the second robot 22. Second pallets 91 witharticles and empty pallets from the second escapement mechanism 170across from the first robot 20 are conveyed to the second escapementmechanism 170 across from the second robot 22. The operation is similarto that across from the first robot 20, except that second pallets 91having articles on them loaded by the first robot 20 will be passedthrough on the second conveyor 28 to the second robot 22. It should beappreciated that if the first robot 20 is not operating, the secondescapement mechanism 170 across from the second robot 22 will onlyrelease empty second pallets 91 when the pallet presence sensor 198 isnot triggered. It should also be appreciated that if the second robot 22is not operating, second pallets 91 will back up to trigger the palletpresence sensor 198 preventing the second escapement mechanism 170across from the second robot 22 from releasing second pallets 91. Whenthis occurs, the pallet presence sensor 198 will turn ON a warning lightat the operator electrical control panel 47, signaling a shutdown. Ifthe operator wishes to continue the operation, it must activate a manualoverride switch (not shown) on the operator electrical control panel 47that will allow the second escapement mechanism 170 across from thesecond robot 22 to pass a second pallet 91 through to another secondescapement mechanism 170a. The second escapement mechanism 170 acrossfrom the second robot 22 at the second load station will only release asecond pallet 91 if pallet presence switch 198 is triggered. The secondescapement mechanism 170 across from the first robot 20 will onlyrelease a second pallet 91 if article present sensor 172 is triggeredand pallet presence sensor 171 is cleared.

Loaded second pallets 91 are conveyed to the second escapement mechanism170a which controls the feed to the shuttle assembly 30. The secondescapement mechanism 170a operates similar to the second escapementmechanism 170a across from the second robot 22 at the second loadstation. Second pallets 91 with articles loaded on them will be passedthrough the shuttle assembly 30. Second pallets 91 without an articlewill trigger a light at the operator electrical control panel 47 toindicate that a second pallet 91 is without an article and shut down thesecond escapement mechanism 170a. The operator must purge the shuttleassembly 30 by activating an override switch on the operator electricalcontrol panel 47 by disengaging the third pallet stopping devices 200with the second pallets 91 to allow them to travel along the secondconveyor 28 and reset the second escapement mechanism 170a as to bedescribed.

Along the shuttle assembly 30, five (loading and unloading) stations arelocated with a third pallet stopping devices 200 and a pallet presenceswitch 252. To begin the sequence of the shuttle assembly 30, the palletpresence sensor 252 adjacent third pallet stopping device 200a must beclear for a predetermined time period to ensure adequate time for allsecond pallets 91 to leave the loading area or have counted five secondpallets 91 passing through this station. The third pallet stoppingdevice 200a will extend triggering the limit switch (not shown) whichsends a signal to the main electrical control panel 46. The panel 46relays a signal to the second escapement mechanism 170a to fire allowingone (1) second pallet 91 to be conveyed to the third pallet stoppingdevice 200a . When a second pallet 91 stops against third palletstopping device 200a, the pallet presence switch 252a will detect orsense the second pallet 91, signaling the third pallet stopping device200b to extend. The third pallet stopping device 200b will extend,triggering its limit switch and signaling the second escapementmechanism 170a to fire, allowing one (1) second pallet 91 to be conveyedto the third pallet stopping device 200b. It should be appreciated thatthe same process occurs until all five stations have a second pallet 91resting against its corresponding third pallet stopping device 200.

When the second pallet 91 stops against the third pallet stopping device200e, the pallet presence switch 252e will detect the second pallet 91and the main electrical control panel 46 will instruct the keeper bar248 to drop, triggering its limit switch (not shown), and signaling thedrive cylinder 220 to be actuated. The drive cylinder 220 moves itspiston rod 226 and drive bar 232 to engage the second pallets 91 pushingthem forward into the pickup or load station for the working table 32.When the second pallets 91 are in the loading station, a limit switch(not shown) is triggered, signaling the third pallet stopping devices200a through 200e to retract.

The working table 32, upon completing its cycle, will check the statusof the terminal clear switches 258 to make sure that the unloadingstations are clear, and then move the finished articles to the unloadingstation. A working table 32 then unclamps the second pallets 91 sendinga signal to the panel 46 which relays the signal to the working table toback out of the unloading stations and move to the loading terminals.

At the loading stations, the working table 32 clamps the second pallets91. The working table 32 then backs out of the loading station andstarts its buffing sequence with the buffing device 34. The panel 46sends the signal to the clamping assemblies 266 to engage the secondpallets. The drive cylinder then retracts pulling the articles andsecond pallets 91 back onto the second conveyor 28. Upon the secondpallets 91 arriving at the retracted position, a signal from a limitswitch (not shown) is sent to main electrical control panel 46 whichrelays the signal to actuate the cylinders to raise the keeper bar 248.Once this is accomplished, another limit switch (not shown) signals themain electrical control panel 46 which relays the signal for the clampassemblies 266 to disengage the flanges 119 of the base member 110 ofthe second pallets 91, allowing the second pallets 91 with finishedarticles to be conveyed to the unloading station 36.

When a second pallet 91 is present at the second escapement mechanism170 at the loading station, the pallet presence switch 171 will betriggered. The main electrical control panel 46 will send a signal tothe unclamp/locating device 186 to disengage and unclamp the ketchmember 140 from the article. The operator will manually remove the partand release the foot pedal 370, signaling the unclamp/locating device186 to retract. The second stopping mechanism 170 at the loading stationwill release the second pallet 91 allowing it to be conveyed back to thesecond escapement mechanism 170 across from the first robot 20, andpermitting a second pallet 91 to be loaded with a new article.

Referring to FIGS. 19 through 22, an alternate embodiment 400 of theshuttle assembly 30, according to the present invention, is shown forcooperating with the moveable working table 32 and a finishing devicesuch as the buffing device 34. The shuttle assembly 400 allows articlesto be manually loaded and unloaded onto pallets such as second pallets91 by an operator and be automatically finished by the moveable workingtable 32 and buffing device 34. It should be appreciated that theshuttle assembly 400 eliminates the use of a conveyor and may be aseparate stand-alone device for use with a moveable working table andfinishing device. It should also be appreciated that more than oneshuttle assembly 400 may be used with a moveable working table andfinishing device.

The shuttle assembly 400 includes a support frame, generally indicatedat 402, which is adapted to rest upon a support surface such as a floor.The support frame 402 comprise a plurality of longitudinally andlaterally spaced and generally vertically orientated support columns 404and 405. The support columns 404 and 405 are generally rectangular andtubular with the support columns 404 having a vertical height greaterthan a vertical height of support columns 405. Each support column 404and 405 is supported upon a generally planar and rectangular supportplate 406. The support columns 404 and 405 are secured to the supportplates 406 by suitable means such as welding. A generally rectangularand tubular support member 107 extends between each support column 404and 405 and is secured thereto by suitable means such as welding. Itshould be appreciated that the support plates 406 may be secured to thefloor by suitable mans such as fasteners (not shown).

The support frame 402 also includes a pair of laterally extendingsupport beams 408 secured to the upper end of the support columns 404.The support beams 408 are generally rectangular and tubular in shapehaving a width greater than a height thereof. The support frame 402further includes a generally planar and triangular plate member 410secured to each support column 404 beneath the support beam 408 by asuitable means such as welding. A cross beam 412 extends longitudinallybetween support columns 404 and is secured to the plate members 410 andsupport beams 408 by suitable means such as welding. It should beappreciated that the plate members 410 and cross beam 412 provideadditional strength to support the support beams 408 in a cantileveredmanner.

The shuttle assembly 400 includes a mounting plate 414 extending betweensupport beams 408 and secured thereto by suitable means such as welding.The mounting plate 414 is generally rectangular and planar in shape andis secured near the free ends of the support beams 408. The shuttleassembly 400 also includes a plurality of skid rails 416 secured to themounting plate 414 by suitable means such as fasteners 418. The skidrails 416 are generally elongated and rectangular in shape and extendlaterally outwardly from the mounting plate 414. The skid rails 416 arespaced along the mounting plate 414 to form a plurality of loading andunloading platforms or stations for guiding movement of pallets (phantomlines) such as second pallets 91 shown in FIG. 13. Each pair of skidrails 416 forms a single loading and unloading station with an open end.The number of loading and unloading stations formed should, of course,correspond to the number of spindles on the moveable working table 32(e.g. five). It should be appreciated, however, that the number ofloading and unloading stations may be varied. It should also beappreciated that the skid rails 416 support and guide the second pallets91.

The shuttle assembly 400 further includes a clamp assembly, generallyindicated at 420, secured to the mounting plate 414 at each loading andunloading station. The clamp assembly 420 is located opposite the openend of the loading and unloading station for engaging and disengagingthe second pallet 91 to removeably secure the second pallet 91 to theshuttle assembly 400. Preferably, the clamp assembly 420 is disposedbetween the skid rails 416 at each loading and unloading station.

The clamp assembly 420 includes a generally horizontally orientatedclamp member 422 having a downwardly extending finger 424 at one endwhich is adapted to engage and disengage a slot or aperture 426 on thesecond pallet 91. The clamp member 422 is pivotally or rotatablysupported by a shaft 428 having a bushing 430 disposed thereabout andextending through an aperture 432 in the clamp member 422. The shaft 428is supported between a pair of longitudinally spaced side member 434.Each side member 434 has a generally vertical portion 436 secured to themounting plate 414 by suitable means such as welding. Each side member434 also has a generally horizontal portion 438 extending away from theclamp member 422. The shaft 428 extends through an aperture 439 in thevertical portion 436 and may be secured thereto by suitable means suchas a fastener 439a.

The clamp assembly 420 also includes a fluid actuated cylinder 440 suchas a pneumatic cylinder having an axially extending piston rod 442. Itshould be appreciated that the piston rod 442 is attached to a moveablepiston (not shown) disposed within the fluid actuated cylinder 440. Thefree end of the piston rod 442 is disposed in a slot 443 in the otherend of the clamp member 422 and pivotally or rotatably connected by apin member 444 extending through an aperture 445 of the clamp member 422to pivot the clamp member 422 between an engaged position (solid lines)and a disengaged position (phantom lines) as illustrated in FIG. 22. Thefluid actuated cylinder 440 is pivotally or rotatably supported by a pinmember 446. The pin member 446 has a bushing 447 at each end and issupported between a pair of longitudinally spaced block members 448. Theblock members 448 are secured to the mounting plate 414 by suitablemeans such as fasteners 449. The fluid actuated cylinder 440 extendsthrough an aperture 450 in the mounting plate 414. The fluid actuatedcylinder 440 is connected by conduits or fluid lines 452 and 454 to asource of fluid pressure (not shown) such as air. The fluid cylinder 440pivots between an extended position (solid lines) and a retractedposition (phantom lines) as illustrated in FIG. 22 in response to fluidpressure. It should be appreciated that the extended and retractedpositions of the fluid actuated cylinder 440 correspond to the engagedand disengaged positions, respectively, of the clamp member 422. Itshould be appreciated that the fluid pressure may be operated by a footpedal or the like by an operator.

Optionally, the clamp assembly 420 may include a stop member 456 securedto one end of a threaded shaft 458. The threaded shaft 458 is generallyvertically orientated and is adjustably secured by suitable fastenerssuch as nuts 460 to a bracket 462. The bracket 462 is generally "Z"shaped and secured to the mounting plate 414 by suitable means such as afastener 464. The stop member 456 limits or stops the downward movementof the clamp member 422 toward the skid rail 416. It should beappreciated that the location of the stop member 456 may be adjustedvertically by threaded shaft 458 and nuts 460.

Referring to FIGS. 19 and 20, the clamp assembly 420 may include anoptional rotating mechanism, generally indicated at 466, mounted on topof the side members 434 for rotating a locking arrangement (not shown)on the pallet. The rotating assembly 466 includes a motor 468 having arotatable shaft 470. The rotating mechanism 466 and locking arrangementare of the type disclosed in copending application, Ser. No. 594,632,filed Oct. 9, 1990 and entitled "INTEGRATED BUFFING AND GRINDINGSYSTEM". It should be appreciated that the motor 468 may be air orelectrically operated and secured to the side members 434 by suitablemeans.

In operation, a second pallet 91 is placed at each loading and unloadingstation upon the skid rails 416. The fluid actuated cylinder 440 isactuated by fluid pressure and extends the piston rod 442 to pivotallymove the clamp member 422 to the engaged position such that the finger424 engages the slot 426 in the pallet 91. Next, an operator loads anarticle to be finished upon each pallet 91. When all the pallets 91 areloaded with articles, fluid actuated cylinders 440 are actuated by fluidpressure to retract the piston rod 442 to pivot the clamp member 422 tothe disengaged position.

The moveable working table 32 then enters the open end of the loadingand unloading stations and moves underneath the second pallets 91. Theworking table 32 clamps the second pallets 91. The working table 32 thenbacks out of the loading and unloading station and starts its finishingsequence with a finishing device such as buffing device 34. When thefinishing sequence is completed, the working table 32 moves the secondpallets 91 through the open end of the loading and unloading station andonto the skid rails 416. The working table 32 then unclamp the secondpallets 91. The fluid actuated cylinders 420 are actuated by fluidpressure to extend the piston rod 442 to pivot the clamp member 422 tothe engaged position. The operator then unloads the finished articlesfrom the second pallets 91. The operation may then be repeated.

The present invention has been described in an illustrative manner. Theterminology which has been used is intended to be in the nature of wordsof description rather than of limitation.

Many modifications and variations of the present invention are possiblein light of the above teachings. Therefore, within the scope of theappended claims, the present invention may be practical otherwise thanas specifically described.

What is claimed:
 1. A shuttle assembly for supporting at least onepallet and adapted to cooperate with a moveable working table,comprising:a frame; means on said frame for providing at least oneloading and one unloading platform having an open end adapted to allowtransfer of the at least one pallet between the loading and unloadingplatform and the moveable working table wherein said means on said framefor providing at least one loading and unloading platform comprise atleast a pair of laterally spaced and longitudinally extending skid railsfor supporting the at least one pallet; clamping means located oppositethe open end for engaging and disengaging the at least one pallet; andmeans for moving said clamping means between an engaged position and adisengaged position with the at least one pallet, wherein said movingmeans comprises a fluid actuated cylinder pivotally mounted to saidframe and a piston rod cooperating with said cylinder and moveablebetween an extended and retracted position to move said clamping meansbetween said engaged and disengaged positions.
 2. The shuttle assemblyas set forth in claim 1 wherein said clamping means comprises a clampingmember pivotally mounted on said frame.
 3. The shuttle assembly as setforth in claim 2 wherein said clamping member has at least onedownwardly extending finger adapted to engage an aperture in the atleast one pallet.
 4. A shuttle assembly for supporting a plurality ofpallets and adapted to cooperate with a moveable working table,comprising:a frame having a mounting plate extending longitudinally; aplurality of skid rails being longitudinally spaced and secured to saidmounting plate for providing a plurality of loading and unloadingplatforms, each of said loading and unloading platforms having an openend adapted to allow transfer of the pallets between the loading andunloading platforms and the moveable working table; clamping meanssecured to said mounting plate and located opposite the open end forengaging and disengaging the pallets; said clamping means comprises aclamping member pivotally mounted on said frame and having a downwardlyextending finger adapted to engage an aperture in the pallets; and afluid actuated cylinder pivotally mounted upon said mounting plate and apiston rod cooperating with said cylinder and moveable between anextended and retracted position to move said clamp member between anengaged and disengaged position with the pallets.
 5. A shuttle assemblyfor supporting a plurality of pallets and adapted to cooperate with amoveable working table, comprising:a frame; a plurality of loading andunloading stations on said frame, each of said loading and unloadingstations including a pair of laterally spaced, longitudinally extendingskid rails for supporting said pallets, each of said loading andunloading stations having an open end for allowing transfer of saidpallets between said loading and unloading stations and said moveableworking table; and a clamp supported by said frame and located oppositesaid open end of each of said loading and unloading stations, each ofsaid clamps having a clamping member which is moveable between anengaged position and a disengaged position by an associated fluidactuated cylinder, such that said clamping member of each of said clampsengages one of said pallets in said engaged position and said clampingmember of each of said clamps disengages one of said pallets in saiddisengaged position.